It was 150 years ago this week that the infamous New York City draft riots, among the bloodiest incidents of mob violence in American history, were finally brought under control with the help of federal troops.

Hundreds died, the police superintendent was almost killed, police stations were burned and City Hall was threatened with destruction by a mob angry over the planned conscription of men for the Union Army in the Civil War.

But unlike many events in city history, no plaque or marker denotes an event that is labeled the largest civil insurrection in American history.

"Nothing, there is nothing," said historian Harold Holzer, an authority on the life of President Abraham Lincoln.

For years, Holzer has led an unsuccessful campaign to get a marker placed to recall the four days of rioting and slaughter that he said targeted African-Americans for especially cruel punishment. The interest is just not there, he said.

"It's the kind of confused event that makes it very difficult to memorialize or turn into a holiday," Jon Grinspan, a history doctoral candidate at the University of Virginia, noted in an email.

A conference of historians on the riots is scheduled for Thursday at the Century Association in Manhattan.

Perhaps the only physical signs left are some graves at Brooklyn's Green-Wood Cemetery of those killed in the rioting, graves that the cemetery's historic-fund guide Ruth Edebohls includes once a year in a special tour.

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While there are no historical plaques for the rioting, the New-York Historical Society is displaying the rescued orphanage Bible and the only wooden selection box used to pick names of draftees to have survive the rioting in the city. The artifacts are among scores featured in Holzer's book "The Civil War in 50 Objects," which is published in conjunction with the historical society.

"It was definitely a race riot, sort of a pogrom in which African-Americans were singled out," said Holzer.

Marauding bands of rioters, described in historical accounts as mostly poorer Irish immigrants who couldn't pay $300 to buy their way out of the draft, captured black men who had the misfortune of being nearby. Some were beaten to death or lynched, their bodies set on fire. Black people were targeted because some saw them as being the cause of a war for which support was ambivalent.

In one particularly harrowing incident, the mob attacked the Colored Orphan Asylum at Fifth Avenue and 43rd Street, which was home to more than 200 African-American children. Police helped get the orphans to safety, including one who rescued the home's Bible before the mob burned the building down.

The riots had a major impact on race relations in New York, said Holzer.

"Until that moment, poor people lived together," said Holzer. He explained that black people set up armed defensive positions in the Weeksville section of Brooklyn, where they remained safe.

Ultimately, the rioting contributed to blacks living years later separately in communities like Harlem, Holzer noted.

Given the relatively peaceful interracial demonstrations following the verdict in the George Zimmerman case, it is an interesting time to remember what happened during the draft riot, said Holzer.

The rioting was quelled with the help of thousands of federal troops, who had been pulled out of the city to fight in places like Gettysburg, Pa., just weeks earlier. The draft did take place in August without further incident.